You call up a friendly voice on the radio, get told about the gliders working the ridge and the danger area that has just gone active, and feel a little safer. But what exactly have you signed up for, and what has that voice promised you? The flight information service is one of the most useful and most misunderstood things a light-aircraft pilot uses, because its help is real but its guarantees are narrow, and in the UK the menu of choices is larger, and more precisely defined, than most people realise.
This is general educational information, not operational, legal, or regulatory advice. Rules differ by authority and change over time. Always verify against current official sources and follow your operator's approved procedures.
What FIS is under ICAO
At the international level, the ICAO Annex 11 (Air Traffic Services) defines the flight information service as "a service provided for the purpose of giving advice and information useful for the safe and efficient conduct of flights". It is one of three air traffic services Annex 11 recognises, the others being air traffic control and the alerting service, and the division matters: air traffic control is the service that prevents collisions and keeps traffic separated, while the flight information service does not. FIS informs; it does not separate.
Annex 11 also says who gets it and what it carries. Flight information service is to be provided to all aircraft likely to be affected by the information and which are either provided with air traffic control service or otherwise known to the relevant air traffic services units. Its content includes pertinent SIGMET and AIRMET information, information on pre-eruption volcanic activity and volcanic ash, the release of radioactive materials or toxic chemicals into the atmosphere, changes in the availability of radio navigation services, changes in the condition of aerodromes and their facilities (including the state of movement areas affected by snow, ice or significant depth of water), and information on unmanned free balloons. Crucially, Annex 11 records that FIS does not relieve the pilot-in-command of any responsibilities; the final decision remains the pilot's. That single sentence is the seed of everything below.
The UK's distinct menu
Most countries provide "a flight information service" broadly in the ICAO shape. The UK does something more specific, and a pilot flying there needs to know it. Under CAP 774, "UK Flight Information Services", the UK offers four named services, and they are, aerodrome services aside, the only air traffic services provided outside controlled airspace within the UK Flight Information Region. These four names are a UK construction, not ICAO or European terminology, so do not expect to hear them abroad. And CAP 774 opens with the governing principle: regardless of the service being provided, pilots are ultimately responsible for collision avoidance and terrain clearance.
Basic Service is the lightest. The controller or flight information service officer gives you generic advice and information, weather, airspace activity, and the like, but you should not expect any form of traffic information, the provider is not required to monitor your flight, and the avoidance of other traffic is solely your responsibility. It is help with situational awareness, nothing more.
Traffic Service is surveillance-based. In addition to a basic service, the controller passes specific surveillance-derived traffic information to help you avoid other aircraft, and may give headings or levels for positioning or sequencing. But the controller is not required to achieve deconfliction minima, and you remain responsible for collision avoidance; the service tells you where the traffic is and leaves the avoiding to you.
Deconfliction Service goes further. Again surveillance-based, it adds traffic information and headings or levels "aimed at achieving planned deconfliction minima". Against unknown, uncoordinated traffic those minima are 5 NM laterally or 3,000 ft vertically. Even so, CAP 774 is candid that controllers cannot guarantee to achieve them and will apply all reasonable endeavours, and that avoidance is ultimately the pilot's responsibility. You may elect not to follow the deconfliction advice, but if you do, you accept responsibility for avoiding that traffic yourself. It is only provided to flights under IFR outside controlled airspace.
Procedural Service is the non-surveillance option. Without a radar-derived picture, the controller provides restrictions, instructions and clearances that, if complied with, achieve deconfliction against other aircraft participating in the procedural service only. It gives neither traffic information nor deconfliction against unknown traffic. It is the service for when there is no usable surveillance, and its protection extends only to the pilots who are all playing by the same procedural rules.
What none of them guarantees
Read those four together and the common thread is stark: no UK flight information service guarantees separation from unknown traffic, and under every one of them the pilot remains ultimately responsible for collision avoidance. Even the Deconfliction Service only aims at its minima and admits it cannot promise them. This is not a UK quirk to resent; it is the honest consequence of providing a service outside controlled airspace, where not every aircraft is talking to anyone or even carrying a transponder. The value of the service is better awareness and, at the higher levels, active help; the value it does not offer is the guaranteed separation that only air traffic control inside controlled airspace provides.
The FAA's flight following
American pilots use a similar idea under a different name, and the name causes confusion. "Flight following" is colloquial; the FAA service is the radar traffic information service, described in AIM 4-1-15, with terminal-area versions in AIM 4-1-18. A controller passes traffic information to a VFR aircraft, but the AIM is explicit that the service "is not intended to relieve the pilot of the responsibility" to see and avoid other aircraft, that many factors including controller workload can prevent it being provided, and that standard radar separation is not provided between VFR aircraft. In substance it sits close to the UK's Traffic Service: useful traffic information, workload-permitting, with see-and-avoid firmly retained.
One separation of terms is worth nailing down, because the acronyms collide. The ICAO/UK/European flight information service is a two-way air traffic service delivered by a human. The FAA's FIS-B, "Flight Information Service-Broadcast" in AIM 4-5-9, is something else entirely: a one-way ADS-B ground broadcast of weather and aeronautical data to the cockpit, with no controller and no two-way exchange. They share three letters and nothing else. The FAA's human equivalent of the ICAO information role is its Flight Service, which handles briefings and en-route information, much as a recorded weather broadcast or an ATIS handles part of that job automatically.
SERA and the FISO
Europe codifies the ICAO service in the Standardised European Rules of the Air: SERA.9001 sets who receives it and states that its reception does not relieve the pilot-in-command of responsibilities and that air traffic control takes precedence over FIS where a unit provides both; SERA.9005 lists what the service includes, transposing the Annex 11 content. This is the single ICAO-shaped service, and it is what the UK's four-tier menu implements and extends. In the UK, a flight information service officer (FISO), heard as callsigns such as "London Information", provides a Basic Service only and is not licensed to provide the Traffic, Deconfliction or Procedural Services, so requesting those from a FISO is asking for something they cannot give. That limitation is itself part of knowing what you have called up.
A worked example
You are flying VFR across open country in UK Class G, and you call the local radar unit. You ask for, and are given, a Traffic Service. Now you know precisely what you have: the controller will pass you surveillance-derived traffic, "traffic north, 3 miles, crossing left to right, indicating 500 feet above", but is not deconflicting you from it, and if you want to avoid it you manoeuvre yourself. You spot a converging light aircraft the controller could not see because it was not showing on surveillance, and you give way under the ordinary rules of the air, because the Traffic Service never promised to keep you apart.
Later you climb into cloud under the instrument flight rules and request an upgrade to a Deconfliction Service. The tone changes: now the controller issues you a heading and a level "for deconfliction", aiming at 5 NM or 3,000 ft from the unknown traffic ahead. You comply, and you are safer for it, but you also understand from CAP 774 that the controller cannot guarantee those minima and that you remain ultimately responsible. Had you declined the turn, you would have taken on the avoidance yourself. Two services, one flight, and at every moment you knew exactly how much protection you had, which is the whole point of knowing the menu.
Common pitfalls
- Thinking FIS keeps you separated. It does not; separation is air traffic control's job, and outside controlled airspace no flight information service guarantees it.
- Treating the four UK services as ICAO terms. Basic, Traffic, Deconfliction and Procedural are UK definitions from CAP 774, not international ones.
- Expecting traffic information under a Basic Service. You should not; avoidance is solely your responsibility, and the provider need not even monitor your flight.
- Reading Deconfliction minima as a promise. The 5 NM or 3,000 ft against unknown traffic is aimed at, not guaranteed, and you stay ultimately responsible.
- Confusing FIS with FIS-B. One is a two-way air traffic service; the other is a one-way ADS-B data broadcast in the US. Same acronym, different thing.
- Asking a FISO for a Traffic or Deconfliction Service. A UK FISO provides a Basic Service only.
In Pilot EFB
Pilot EFB is a study and planning companion for the ground half of this: understanding the services here in Learn, and keeping the weather and airspace picture, decoded ATIS and recorded broadcasts, and any temporary airspace restrictions you have briefed, in one offline-first place so a briefing you have already pulled stays readable. It does not talk to air traffic control, provide any flight information service, or show you live traffic; the radio call, the service you request and the separation you do or do not have are matters between you and the unit on frequency. Pilot EFB is not a certified Electronic Flight Bag, so treat it as a study and planning aid and rely on the air traffic service and your own lookout in the air.